For example, for a gasification facility, a carbonaceous fuel gasification apparatus (coal gasification apparatus) is known where a carbon-containing solid fuel such as coal is supplied into a gasification furnace, and the carbon-containing solid fuel is partially combusted so as to gasify the carbon-containing solid fuel, thus producing a combustible gas.
In an integrated coal gasification combined cycle (hereinafter referred to as “IGCC”) facility, a produced gas produced by a gasification apparatus using a carbon-containing solid fuel such as coal is purified by a gas purifying device, thus forming a fuel gas and, thereafter, the fuel gas is supplied to a gas turbine facility so as to generate power. The gasification facility is provided with finely powdered fuel supply hoppers (powder supply hoppers) for supplying a finely powdered fuel (powder) such as pulverized coal to the gasification furnace. In the case where coal is used as a carbon-containing solid fuel, the finely powdered fuel supply hopper functions as a pulverized coal supply hopper, and is supplied with pulverized coal under atmospheric pressure from a mill, which pulverizes coal into a powdered state, via a pulverized coal bin. When a predetermined amount of pulverized coal is accumulated in the pulverized coal supply hopper, the pulverized coal supply hopper is hermetically sealed and, thereafter, is pressurized to a predetermined pressure by a pressurizing gas such as nitrogen gas. The reason for pressurizing the pulverized coal supply hopper is as follows. That is, the gasification furnace to which pulverized coal is to be supplied is in a pressurized state, so that the pulverized coal supply hopper is pressurized so as to maintain the pressure in the pulverized coal supply hopper equal to or greater than the pressure in the gasification furnace. The pulverized coal supply hopper which is pressurized to a predetermined pressure supplies pulverized coal into the gasification furnace due to a pressure difference between the pulverized coal supply hopper and the gasification furnace. When supply of pulverized coal is finished, a connection between the pulverized coal supply hopper and the gasification furnace is cut. Thereafter, a pressure in the pulverized coal supply hopper is returned to the atmospheric pressure, and the pulverized coal supply hopper receives pulverized coal from the pulverized coal bin again. A plurality of pulverized coal supply hoppers, which repeatedly perform such pressurization and depressurization, are provided. By switching between the pulverized coal supply hoppers, pulverized coal is continuously supplied to the gasification furnace (see PTL 1).
In such a pressurizing system for pressurizing the pulverized coal supply hoppers, buffer tanks are installed so as to shorten a pressurization time for the pulverized coal supply hoppers and to reduce a capacity of a pressurizing nitrogen compressor, and the pulverized coal supply hoppers are pressurized using nitrogen of high pressure which is collected in the buffer tanks.
FIG. 9 shows a pressurizing system for a pulverized coal supply hopper shown in FIG. 2 of PTL 2. Two pulverized coal supply hoppers 103, which supply pulverized coal to a gasification furnace 100, are provided in parallel. Each of the respective pulverized coal supply hoppers 103 is supplied with nitrogen gas through valves 106, 107 from buffer tanks 104, 105 in which the nitrogen gas is collected. Further, a pressurizing gas (nitrogen gas) is emitted to the atmosphere from each of the respective pulverized coal supply hoppers 103 through valves 108.